The self-propagation high-temperature synthesis of ultrafine high purity tungsten powder from scheelite

1996 ◽  
Vol 11 (7) ◽  
pp. 1825-1830 ◽  
Author(s):  
J. C. Jung ◽  
S. G. Ko ◽  
C. W. Won ◽  
S. S. Cho ◽  
B. S. Chun
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
High Purity ◽  
Tungsten Powder ◽  
The Self ◽  
Molar Ratio ◽  
Temperature Synthesis ◽  
Complete Reduction ◽  
High Temperature Synthesis ◽  
Hcl Solution

High-purity tungsten was prepared by the self-propagating high-temperature synthesis (SHS) process from a mixture of CaO · WO3 and Mg. The complete reduction of CaO · WO3 required a 33% excess of magnesium over the stoichiometric molar ratio Mg/CaO · WO3 of 3: 1. The MgO and CaO in the product were leached with an HCl solution. The product tungsten had a purity of 99.980% which was higher than that of the reactants. The high purity results because the nontungsten reactants and products are volatilized by the high temperatures generated during the rapid exothermic SHS reaction and are dissolved during HCl leaching of the product.

Magnesium reduction of WO3 in a self-propagating high-temperature synthesis (SHS) process

1995 ◽  
Vol 10 (4) ◽  
pp. 795-797 ◽  
Author(s):  
Seog Gueon Ko ◽  
Chang Whan Won ◽  
Byong Sun Chun ◽  
H.Y. Sohn
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
High Purity ◽  
Exothermic Reaction ◽  
The Self ◽  
Molar Ratio ◽  
Temperature Synthesis ◽  
Complete Reduction ◽  
High Temperature Synthesis ◽  
Hcl Solution

High-purity tungsten was prepared by the self-propagating high-temperature synthesis (SHS) process from a mixture of WO3 and Mg. The MgO in the product was leached with an HCl solution. The complete reduction of WO3 required a 33% excess of magnesium over the stoichiometric molar ratio Mg/WO3 of 3. The product tungsten had a purity of 99.980% which was higher than that of the reactant WO3. This is because the impurities were either volatilized at the high temperatures generated during the rapid exothermic reaction or dissolved into the HCl solution during leaching.

EFFECT OF BN/Ti RATIO ON THE REACTION SYNTHESIS OF TiB2-TiNx CERAMICS

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1172-1178 ◽  
Author(s):  
LEI ZHAN ◽  
PING SHEN ◽  
QI CHUAN JIANG
Keyword(s):  
High Temperature ◽  
Wave Velocity ◽  
Combustion Temperature ◽  
The Self ◽  
Molar Ratio ◽  
Reaction Synthesis ◽  
Temperature Synthesis ◽  
High Temperature Synthesis

The effects of BN / Ti molar ratio on the self-propagating high-temperature synthesis (SHS) reaction behaviors and final products in the Ti - BN system were experimentally investigated. With an increase in the BN / Ti ratio, the combustion temperature and wave velocity first increase and then decrease with the maximum values displaying at BN / Ti =0.67. A substoichiometric TiN 1- x was obtained for BN / Ti <0.67, and a stoichiometric one was produced for BN / Ti =0.67. Moreover, the microstructure photographs of the products reveal that with the increase of the BN / Ti ratio, the grains of the ceramic phases tend to be finer.

Influence of Cu addition on the self-propagating high-temperature synthesis of Ti5Si3 in Cu–Ti–Si system

2008 ◽  
Vol 111 (2-3) ◽  
pp. 463-468 ◽  
Author(s):  
H.Y. Wang ◽  
S.J. Lü ◽  
M. Zha ◽  
S.T. Li ◽  
C. Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
The Self ◽  
Temperature Synthesis ◽  
High Temperature Synthesis

Self-propagating high-temperature synthesis microalloying of MoSi2 with Nb and V

2003 ◽  
Vol 18 (8) ◽  
pp. 1842-1848 ◽  
Author(s):  
F. Maglia ◽  
C. Milanese ◽  
U. Anselmi-Tamburini ◽  
Z. A. Munir
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Tetragonal Phase ◽  
Synthesis Method ◽  
The Self ◽  
Alloying Elements ◽  
Alloying Element ◽  
Temperature Synthesis ◽  
Starting Mixture ◽  
High Temperature Synthesis

Microalloying of MoSi2 to form Mo(1−x)MexSi2 (Me = Nb or V) was investigated by the self-propagating high-temperature synthesis method. With alloying element contents up to 5 at.%, a homogeneous C11b solid solution was obtained. For higher contents of alloying elements, the product contained both the C11b and the hexagonal C40 phases. The relative amount of the C40 phase increases with an increase in the content of alloying metals in the starting mixture. The alloying element content in the hexagonal C40 Mo(1−x)MexSi2 phase was nearly constant at a level of about 12 at.% for all starting compositions. In contrast, the content of the alloying elements in the tetragonal phase is considerably lower (around 4 at.%) and increases slightly as the Me content in the starting mixture is increased.

scholarly journals Кластеризация марганца в ZnS : Mn, Mg, полученного методом высокотемпературного самораспространяющегося синтеза

2020 ◽  
Vol 54 (3) ◽  
pp. 259
Author(s):  
Ю.Ю. Бачериков ◽  
И.П. Ворона ◽  
О.Б. Охрименко ◽  
В.П. Кладько ◽  
А.Г. Жук ◽  
...  
Keyword(s):  
High Temperature ◽  
Luminescence Band ◽  
Lattice Strain ◽  
Nonuniform Distribution ◽  
The Self ◽  
Manganese Ions ◽  
Photoluminescence Band ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Mn Concentration

Abstract The ZnS:Mn, Mg powder is fabricated by self-propagating high-temperature synthesis with the simultaneous introduction of Mn and Mg impurities. It is found that the simultaneous introduction of Mn and Mg impurities leads to the nonuniform distribution of manganese forming regions with a lower and higher Mn concentration. In the latter case, the manganese ions form paramagnetic clusters. At the same time, numerous centers of self-activated luminescence form in the synthesized ZnS:Mn, Mg due to mechanical stress and lattice strain. Additional annealing leads to a more uniform Mn distribution in the formed ZnS:Mn, Mg phosphor, which is accompanied by an increase in the intensity of the manganese photoluminescence band and quenching of the self-activated luminescence band.

Microstructural aspects of the self-propagating high temperature synthesis of hexagonal barium ferrites in an external magnetic field

2000 ◽  
Vol 10 (8) ◽  
pp. 1925-1932 ◽  
Author(s):  
Louise Affleck ◽  
Marco D. Aguas ◽  
Ivan P. Parkin ◽  
Quentin A. Pankhurst ◽  
Maxim V. Kuznetsov
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
External Magnetic Field ◽  
The Self ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Barium Ferrites
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